Alcohol use disorder (AUD) and mild traumatic brain injury (mTBI) impact functional abilities. AUD occurs in up to 35% of Veterans with mTBI. Evidence suggests that co-occurrence of AUD and mTBI (AUD+mTBI) leads to an exacerbation of brain dysfunction, symptom manifestation, and ultimately, functional disability. Alcohol- related characteristics are operationally defined per AUD symptoms and outcomes including, but not limited to, alcohol consumption, alcohol craving, and AUD severity. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulatory treatment that will soon be a treatment option at 30 VAs nationwide. Preliminary rTMS efficacy is demonstrated for AUD alone and mTBI alone using a variety of neural targets. rTMS is, thus, a promising treatment for AUD+mTBI. The objectives of this study are to 1) identify neural targets (i.e. site of stimulation) associated with both alcohol-related characteristics and self-reported functional disability, and 2) assess preliminary efficacy and sustainability of a high frequency rTMS protocol applied to these customized neural targets relative to the commonly used left dorsolateral prefrontal cortex (DLPFC) site. Addressing these objectives are essential steps towards our long-term research goal [to customize and clinically implement a rTMS treatment] that can improve brain function resulting in optimal recovery for Veterans with AUD+mTBI. To address the first study objective, Veterans will be recruited and classified into one of two groups based on structured-interviews, self-report measures, and neuropsychological assessments: 1) AUD+mTBI, and 2) [Veteran controls] without a history or symptoms of mTBI or AUD. Alcohol-related characteristics will be assessed through objective measures of alcohol use, self-report measures, and structured interviews. Self-reported functional disability will be assessed using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS). Neuroimaging metrics will be assessed through a multi- modal, functional and structural Magnetic Resonance Imaging (MRI) scan. Participants will complete a functional MRI (fMRI) protocol where brain activation will be measured in response to viewing images related to alcohol, compared to neutral images. Advanced neuroimaging procedures to determine the structural integrity of white matter fibers in the brain and spontaneous activity in brain networks, a process called resting state functional connectivity (rsFC), will also be conducted. To address the second study objective, AUD+mTBI Veterans will receive rTMS at one site randomly assigned from a set of 4 sites: 3 customized neural targets identified in this study, and the commonly used left DLPFC. AUD+mTBI Veterans will complete 10 PLACEBO, then 10 ACTIVE rTMS sessions in a within-subjects design. Follow-up WHODAS assessments will occur at 2- weeks, 1-month and 6-months post-ACTIVE rTMS. Aim 1 will identify unique neural targets for rTMS to treat AUD+mTBI by determining which multi-modal neuroimaging metrics are most strongly associated with both alcohol-related characteristics and functional disability. Aim 2 will [test preliminary efficacy of high-frequency rTMS administered over the customized neural targets] to treat functional disability among Veterans with AUD+mTBI. Aim 3 will assess sustainability of rTMS effects on functional disability for Veterans with AUD+mTBI. We hypothesize that for Veterans with AUD+mTBI, there are neural substrates of AUD related to functional disability, and that neuromodulation of these substrates will be related to gains in functional disability. Our innovative approach represents an advancement in the field of neurorehabilitation because a neural target will be systematically defined, using multi-modal neuroimaging, prior to preliminary rTMS efficacy and sustainability testing. These steps are necessary to customize rTMS treatment for a population of Veterans with co-occurring conditions and unique health care needs. Thus, the outcomes of this research will optimize function for Veterans with AUD+mTBI.